Process for drying natural sodium carbonate



10 adopt such treatment.

Patented Sept. 13, 1932 UNITED STATES WILLIAM FRED sEYER, or VANCOUVER,BRITISH COLU IA, CANADA.

rnoonss FOR marine NATURAL soDIUMcARBoNA'rE 7 N Drawing. Applicationfiled April- 10, 1929, Serial 354,174, and in Canada A rn 10,1928.

'My invention relates to a certain new and useful process of dryingsodium carbonate dekahydrate or commonly known'as sal soda, or sodiumsulphate. I

5 While it is known that sodium carbonate and sodium sulphatedekahydrates can be dried in small quantities by heating them toevaporate their moisture contents, it has:

not been found commercially practical to The sodium carbonates andsodium sulphates are essentially similar in characteristics, so that theei iicient treatment of one will be found equally efiicient with theother and in a like manner the difficulties to be overcome in drying aresubstantially identical.

Sodium carbonate and sodium sulphate dekahydrates have a combined watercon tent of 66% and 56% respectively and will melt at 3 1- degreescentigrade at atmospheric pressure, on melting the salt an unstablemodification or a heptahydrate results,

which breaks down into a stable modification or a monohydra-tc. Themonohydrate be- 2 ing more soluble in cold than in hot water prohibitsthe use of heated metallic surfaces as drying agents, since a salinescale or crust forms thereon and becomes substantially insoluble, thiscrust also forming so a non-conductor of heat and cold so that the heatemployed to heat the coated surface is incapable of being'efiectivelyused for evaporating the combined moisture from the salt. By providing asource of violent agitation the scaling may be reduced but not entirelyavoided, but if small amounts of finely divided foreign substances suchas 001- loidal mud are present, the heated surfaces again become coatedand the process hamp- 40 cred.

By my process I take one part of dekahy mm. The subjection of either ofthe salts P rENr O F CE" to a drying process for a suitable time willresult in all but about one tenth of one per cent of combined waterbeing driven'ofi'. Physically adhering water, if any, will also bedriven oft; V i

The value of the coating of th e dekahydrateparticles lies in providingthem with a substance which restricts or controls the speedofevaporation of the combined moisture therefrom and prevents the. rapidevaporation of moisture and melting of the salt which causes what istechnically known j drying a dekahydrate salt which consists of reducingvits granules to a diameter between 0.5 mm; and '2mm., coating the saidgranules with a dry salt of the same kind and of-eva-porating themoisture fromthe mass.

Dated at Vancouver, B. 0., this 3rd day of April, 1929.

7 WILLIAM FRED SEYER. i r

